Buggy code:
public class GroupsController implements Initializable { @ FXML private TitledPane manageGroups ; @ FXML private ListView groups ; @ FXML private ListView members ; @ FXML private TextField groupSelected ; @ FXML private TextField newGroupName ; @ FXML private Button addGroupBtn ; @ FXML private TextField addUserName ; @ FXML private Button addUserBtn ; @ FXML private Button deleteGroupBtn ; @ FXML private Button deleteMemberBtn ; @ FXML private Button finishBtn ; private MainController application ; private final ObservableList obsGroupsList = FXCollections . observableArrayList ( ) ; private final ObservableList obsMembersList = FXCollections . observableArrayList ( ) ; List < Group > listGroups = null ; public void setApp ( MainController application ) { } @ FXML public void initialize ( URL location , ResourceBundle resources ) { } public void loadGroups ( ) { } @ FXML public void changeGroupName ( ActionEvent event ) { } @ FXML public void deleteGroup ( ActionEvent event ) { } @ FXML public void deleteMemberFromGroup ( ActionEvent event ) { } @ FXML public void addNewGroup ( ActionEvent event ) { } @ FXML public void addMemberInGroup ( ActionEvent event ) { if ( Strings . isNullOrEmpty ( addUserName . getText ( ) ) ) { showWarningDialog ( "Veuillez<seq2seq4repair_space>entrer<seq2seq4repair_space>le<seq2seq4repair_space>login<seq2seq4repair_space>de<seq2seq4repair_space>l'utilisateur." ) ; } else { String selectedGrp = groups . getSelectionModel ( ) . getSelectedItem ( ) . toString ( ) ; for ( Group g : listGroups ) { if ( g . getNom ( ) . equals ( selectedGrp ) ) { Boolean inGroup = false ; for ( User u : g . getUsers ( ) ) { if ( addUserName . getText ( ) . equalsIgnoreCase ( u . getLogin ( ) ) ) { showWarningDialog ( "Ajout<seq2seq4repair_space>impossible:<seq2seq4repair_space>L'utilisateur<seq2seq4repair_space>existe<seq2seq4repair_space>déjà<seq2seq4repair_space>dans<seq2seq4repair_space>le<seq2seq4repair_space>groupe<seq2seq4repair_space>!" ) ; inGroup = true ; return ; } } if ( ! inGroup ) { User user = checkIfFriend ( addUserName . getText ( ) ) ; if ( user != null ) { application . getIHMtoDATA ( ) . addUserInGroup ( user , g ) ; obsMembersList . add ( user . getLogin ( ) ) ; showInformationDialog ( ( ( user . getLogin ( ) ) + "<seq2seq4repair_space>a<seq2seq4repair_space>été<seq2seq4repair_space>ajouté<seq2seq4repair_space>dans<seq2seq4repair_space>le<seq2seq4repair_space>groupe<seq2seq4repair_space>avec<seq2seq4repair_space>succès." ) ) ; addUserName . clear ( ) ; return ; } else { <START_BUG> showWarningDialog ( "Ajout<seq2seq4repair_space>impossible:<seq2seq4repair_space>L'utilisateur<seq2seq4repair_space>n'est<seq2seq4repair_space>pas<seq2seq4repair_space>votre<seq2seq4repair_space>amis<seq2seq4repair_space>ou<seq2seq4repair_space>n'existe<seq2seq4repair_space>pas." ) ; <END_BUG> return ; } } } } } } private void displayUsers ( String groupName ) { } private void disableFields ( Boolean b ) { } @ FXML private void finish ( ) { } private User checkIfFriend ( String login ) { } }

Fix:
showWarningDialog ( "Ajout<seq2seq4repair_space>impossible:<seq2seq4repair_space>L'utilisateur<seq2seq4repair_space>n'est<seq2seq4repair_space>pas<seq2seq4repair_space>votre<seq2seq4repair_space>ami<seq2seq4repair_space>ou<seq2seq4repair_space>n'existe<seq2seq4repair_space>pas." ) ;